| 摘要 |
PURPOSE:To keep a surge voltage protecting function and also to reduce the ON resistance of a MOS transistor Tr for a high side switch in order to reduce the power loss of a high side switch circuit. CONSTITUTION:A high side switch circuit contains a high side switch MOS Tr1 and surge input detection circuit 10 which detects the surge voltage of levels higher higher than the maximum rated power voltage. In such a constitution, the voltage boosted by a booster circuit 20 is fed back to the gate of a MOS Tr2 which protects the surge voltage higher than the maximum rated power voltage. Thus the voltage of the Tr2. can be reduced and the voltage supplied to the circuit 20 can be increased up to a level approximately to the power voltage. As a result, the voltage boosted effectively to the power voltage is supplied to the Tr1. Thus it is possible to keep a surge voltage protecting function, to reduce the ON resistance of the Tr1, and also to reduce the power loss of the switch circuit. |
